The most important single solvent used by dry cleaners in the United States is tetrachloroethylene (Cl.sub.2 --C.dbd.C--Cl.sub.2), more commonly known as perchlorethylene or "perc." Perc is a liquid at room temperature and pressure, and is mostly used in closed-to-atmosphere systems that are a part of commercial dry cleaning machines. Perc losses mainly occur through ventilation, waste disposal and residual loss on garments being cleaned. The loss of perc results in a sweet odor that is common in and near virtually all dry cleaning plants.
When sufficient perc has been lost by a dry cleaning plant, additional perc is ordered from a distributor. The distributor typically obtains the perc from a manufacturer and stores it in large storage tanks. Delivery from the distributor to the dry cleaning plant is frequently done with tanker trucks. In a manner similar to the delivery of home heating oil, these trucks are driven to a point near the plant. A perc transfer hose is extended from the truck to the plant's storage tank inlet, which is well inside the dry cleaning plant.
This current delivery method has many drawbacks. First, perc is a volatile organic compound (VOC). Beginning in December 1992, OSHA regulations will require engineering controls to achieve a maximum permissible exposure level (PEL). The current delivery method uses an open-to-atmosphere hose fitting which is merely inserted into the plant's storage tank inlet. Using this method, these 1992 limits cannot be met.
Second, the relatively long hose between the tanker truck and the dry cleaning plant is subject to rupture or leakage because of non-obvious wear, vandalism and accident. The perc discharge resulting from such rupture or leakage causes uncontrolled loss of the solvent and creates personal safety, environmental and traction hazards.
Third, the current delivery method often requires a specialized and expensive tanker truck.
Fourth, large spills can occur in the event of a traffic accident that ruptures the tank on the truck.
Other delivery methods do not require the use of tanker trucks, but have other drawbacks. Perc may be delivered in fifty-five gallon drums. The distributor may off-load these drums using a pump suction tube that is moved from drum to drum for each delivery. Alternatively, the drums may be emptied by dry cleaners themselves through the use of manual drum pumps or small electric transfer pumps and hoses. Many dry cleaning establishment proprietors, however, would rather not be responsible for such emptying, and would prefer to leave transfer in the hands of the distributor.
Several U.S. patents are cited as background for this invention. De Prato et al. U.S. Pat. No. 3,075,662 was issued on Jan. 29, 1963, and is entitled "Hand Truck " This patent describes a hand truck which may be knocked down and reassembled, and in which a wheel shaft interlocks the various parts in a fixed position.
Lisciani U.S. Pat. No. 3,384,132 was issued on May 21, 1968, and is entitled "Flammable Liquid Transfer Station." The invention described depends upon a diaphragm and spring arrangement to move the flammable liquid.
Piecuch U.S. Pat. No. 3,920,056 was issued on Nov. 18, 1975, and is entitled "Portable Automatic Drum Filling Apparatus." The invention relies upon a product level detecting assembly including a filling nozzle and a pair of fluidic product level sensing probes.
Healey et al. U.S. Pat. No. 4,053,001 was issued on Oct. 11, 1977, and is entitled "Method for Charging a Fire Protection System." The method invention described in this patent requires weighing of the fire-extinguishing agent that is being recharged. The apparatus described in this patent requires fluid heating or cooling means.
Henderson U.S. Pat. No. 4,144,915 was issued on Mar. 20, 1979, and is entitled "Liquid Supply Measuring and Dispensing Apparatus." This apparatus claims and requires a dispensing nozzle below the bottom wall of a liquid compartment, nozzle operating means and shut-off means in the dispensing nozzle.
Freeman U.S. Pat. No. 4,195,672 issued on Apr. 1, 1980, and is entitled "Portable Liquid Pesticide Transfer Assembly." This device is disclosed as being typically mounted to a truck. Most of its embodiments also require a complex valve system.
Crumby U.S. Pat. No. 4,741,368 was issued on May 3, 1988, and is entitled "Returnable Container for Liquid Chemicals and Fitting Therefor." The device of this invention discloses a fitting for mounting in the lid of a closed container for dispensing liquid chemicals.
Nice U.S. Pat. No. 4,796,677 was issued on Jan. 10, 1989, and is entitled "Apparatus for Facilitating Liquid Transfer From a Drum." This apparatus is not wheeled or mobile and requires a receptacle, including a conical member.
Hult et al. U.S. Pat. No. 4,888,849 was issued on Dec. 26, 1989, and is entitled "Wheeled Hand Cart for Wet/Dry Utility Vacuum Cleaner." This device requires a handle interconnecting two separate upright handle sections for facilitating movement of the drum of the vacuum cleaner.
Solomon et al. U.S. Pat. No. 4,890,983 was issued on Jan. 2, 1990, and is entitled "Above-Ground Storage System." This device is apparently non-movable, and requires a tank within a tank.
Biehl U.S. Pat. No. 4,932,445 was issued on Jun. 12, 1990, and is entitled "Subsurface Filler." The invention disclosed in this patent is for the subsurface filling of a container with a liquid from a liquid source using a pneumatic cylinder apparatus.
Other patents of general interest include Solomon et al. U.S. Pat. No. 4,948,340, issued on Aug. 14, 1990, and entitled "Above-Ground System"; Evenson U.S. Pat. No. 4,924,898, issued on May 15, 1990, and entitled "Vacuum Assisted Material Mover"; and Apel U.S. Pat. No. 4,875,906, issued on Oct. 24, 1989, and entitled "Partial Oxidation of Low Heating Value Hazardous Waste Petroleum Products."